Matt's RV-7 Project

Here's the propeller governor, a PCU500X. This guy is basically an speed-controlled oil pump, which controls the pressure of the oil being pumped through the hollow crankshaft, and thus sets the pitch of the propeller blades to hold the desired RPM. I started to explain this to Mary but she was too distracted to endure another of my lectures about aviation theory, so I just told her "it costs a thousand dollars and makes the airplane go like hell."

I had to cut off the safety wire, loosen the screws, and rotate the shaft to the correct angle to fit Van's cable bracket. Here it is after I redid the safety wire:

I used my cool new Milbar reversible safety wire pliers to twist the new lockwire, and I must say the improvement in my safety wire workmanship is noticeable compared to when I was using the old, cheap pliers. I guess once again I learn that quality tools make a difference.

I wiped down the surface of the governor drive pad, and removed the caps covering the drive gear and the oil ports:

Likewise, I cleaned the mating surface on the governor and removed the plastic plugs from it too. I made sure to take these photos so I don't have to wonder, "did I really remember to remove those plugs before I bolted on the governor?"

The instruction sheet that comes with the governor says to coat both sides of the included gasket with "a suitable release agent". I dithered on this for a while before finding an old RV-List posting mentioning that Van's preferred substance is plain old fuel lube. I guess the idea here is to make it possible to remove the old gasket if you have to remove the governor, and not to put something on there to enhance the quality of the seal (e.g. Permatex).

Then I bolted the governor and cable bracket to the engine, using star washers under the nuts. Due to the clearances involved I had to use a crow's foot on my torque wrench when tightening the nuts, but that was no big deal.

Here's the model info and serial number, in case I ever need it:

Still waiting on one last box of parts to arrive before this weekend's building session, but in the meantime I spent some time getting familiar with the engine and planning what I need to do before I bolt it to the airplane.

Here's a view of the accessory case on the back of the engine. Clockwise from the left we have the left magneto (black thing with red wires coming out of it), oil filter, vacuum pump drive pad, right magneto drive pad (unused, covered with a circular plate), prop governor drive pad (with cable bracket in place for a test fit), and engine-driven fuel pump (silver thing with blue fitting cap). The hexagonal silver thing in the approximate center of the accessory case is the vernatherm valve (basically an oil thermostat). Above and to the left of the vernatherm is the oil temperature transducer port, directly above is the tach drive pad, and below and to the right is the supply port to the oil cooler.

Closeup view of the right side of the accessory case, showing the vacuum pump and magneto drive pads, and the supply port to the oil cooler. Also visible is the port for the oil pressure gauge – it's the small hole with a red plug threaded into it, just above the magneto drive pad. (Sorry, all my pipe plugs are the same color as the engine itself, which makes them not photograph well)

Closeup view of the left side, looking past the magneto. Here you can see the return port from the oil cooler, which hides behind the oil filter. In fact I'll probably have to remove the filter to get a fitting on there.

Since this engine has a right-angle oil filter adapter, it uses a CH48108-1 filter, which has a built-in check valve. That should help keep oil changes from becoming a major environmental hazard, which has not always been the case with other airplanes I've owned. These filters are also about ninteen bucks each, but that's aviation for you.